A foundation composition can be applied to the face and other parts of the body to even skin tone and texture and to hide pores, imperfections, fine lines and the like. A foundation composition is also applied to moisturize the skin, to balance the oil level of the skin and to provide protection against the adverse effects of sunlight, wind and the harsh environment.
Make-up compositions are generally available in the form of liquid or cream suspensions, emulsions, gels, pressed powders or anhydrous oil and wax compositions.
U.S. Pat. No. 3,444,291 discloses a method of filling and camouflaging skin cavities by applying a composition which includes 65 to 75 parts by weight of a microcrystalline wax and about 25 to 35 parts of a mineral oil. The composition includes a colourant, preferably a coal tar dye, for example, D &C Red No. 17, which matches the colour of the user's skin.
A spreadable, flowable and greaseless cosmetic cover-up composition is taught in U.S. Pat. No. 4,486,405. That composition is characterized by the presence of a first and a second alkoxylated surfactant present in substantially the same concentration.
U.S. Pat. No. 4,804,532 recites a facial cosmetic powder which utilizes crystalline silica in much lower concentration than that employed in the then prior art compositions. This powder, used as a blush or a facial coating, is said to be effective in hiding skin wrinkles, lines and pores. The composition is a mixture of a colour phase and a diluent phase. The colour phase is formed by blending crystalline silica with colourants. The resultant colour phase is mixed with the diluent phase, essentially formed from nacreous materials such as talc and mica, to form the composition.
The use of a foundation composition which has a significantly high concentration of nacreous material is taught in U.S. Pat. No. 3,978,207. This foundation, a pressed powder composition, is characterized by the presence of a nacreous material such as mica and a binder oil which provides a frosted pearl effect, that is, a lustrous look. The colour of this foundation is provided by the nacreous material.
U.S. Pat. No. 4,659,562 discloses a cosmetic make-up composition which includes, as a binding agent, an intimate mixture of from 5 to 95 weight percent of a mixture of finely divided silica and about 5 to 95 weight percent of finely divided polyethylene fibres. The composition is recited to maintain its uniformity over the areas of the skin to which it is applied. That is, it is said to be "creaseproof". The composition of the '562 patent includes colourant in admixture with nacreous agents.
Nakamura et al., Preprints of the XIVth I.F.S.C.C. Congress, Barcelona, 1986, Vol. I, 51-63 (1986) describes a novel make-up composition utilizing spherical silica and polydimethyl siloxane. This combination is recited to provide a foundation which reduces wrinkle visibility to a greater extent than make-up foundations with which it was compared. This reduction in wrinkle visibility is caused by optical blurring enhanced by the novel use of spherical silica and polydimethyl siloxane.
U.S. Pat. No. 5,143,722 discloses a cosmetic make-up composition comprising water-in-oil emulsions comprising pigment coated with polysiloxane, a silicone phase, a water phase and a polydiorganosiloxane-polyoxyalkylene copolymeric surfactant.
Pigments are incorporated into cosmetic compositions to provide colour, coverage and enhanced skin appearance. For formulation of pigmented cosmetic emulsion compositions it is preferable to incorporate coated pigments. Unlike uncoated pigments, coated pigments, e.g. silicone-coated pigments, have the advantage that they are "wettable" in silicone oils.
Poly(methylhydrogen) siloxanes are known for use as coatings for pigments which are suitable for use in cosmetic compositions. Poly(methylhydrogen) siloxanes contain reactive hydrogen functionalities which provide substantivity to the pigment. However, a common unwanted side reaction of these materials when used in formulations in which water or alcohol is present is nucleophilic attack on residual --Si--H functionality to generate hydrogen gas as shown below: EQU --SiH+ROH--SiOR+H.sub.2
where ROH is water or alcohol.
The production of hydrogen gas caused by the above reaction has been known to give rise to undesirable "bubbling" in formulations where pigments coated with silicon hydride-containing polysiloxanes are used in the presence of water or alcohol at acidic pH. The compositions according to the present invention seek to solve this problem.
Since acidic skin care agents such as salicylic acid are most active at low pH (when a high concentration of free acid is present in solution) it would be desirable to deliver the agent from an aqueous phase at a pH at which it exists significantly in protonated form. It is accordingly a primary object of this invention to provide a cosmetic composition comprising a low pH aqueous solution of an acidic skin care active, which at the same time does not give rise to undesirable evolution of hydrogen gas.
It is also an object of the invention to provide a cosmetic composition having improved product stability.
It is a further object of the present invention to provide a cosmetic composition having improved anti-acne activity.